Archive for August 19th, 2012


NGC 6645–the cosmic maw

August 19, 2012

I was out hunting Herchels last night and observed the open cluster NGC 6645 for the first time. From my notebook:

Fairly large open cluster. Not sparse, loads of stars, but all are about equally dim–none really jump out. Has an unusual dark spot in the middle like a mouth or the entrance to a cave. That plus five radiating chains of stars make it look like a howling monster.

This didn’t occur to me until today, but I finally realized which monster it put me in mind of–the Beholder from D&D. This sketch gives a sense of its appearance, although it does vary a bit with aperture–that artist saw “a pretty faint unresolved gray haze with about 30 dim stars visible” whereas the 10-inch resolved it completely, with mini-clusters around the central hole and long chains of stars radiating away like nerve endings from a cartoon neuron.

Anyway, this open cluster is well-placed in the early evening, it’s not hard to find, and it has a lot of character. Well worth tracking down. You can even generate a custom finder chart for it using the interactive star chart at, which I just learned about.

What does it look like to you?